Presently the systems which drive box blanks through a printer/slotter and a follow-on folder are made to operate at substantially the same speed through a direct drive or tack generator system which drives all sections of the printer and the folder on a 1:1 basis. It was thought that the reason that it was necessary to drive the box blanks at the same rate was to avoid jam ups or problems in registration when the box blanks were conveyed from the printer/slotter to the folding system. When off-axis running causes tilt and jam ups, it would sometimes take at least twenty minutes to clear the jam thereby completely shutting down the entire system.
This is especially a problem when lock bottom boxes are printed and then folded, due to the fact that fingers must come down and stop portions of the lock bottom box and fold them along diagonals while the box blank is running in a given direction. The lock bottom boxes, in general, are folded at a much slower rate than are other boxes due to the fingers which lift the panels as they come out of the printer, with the lifter fingers of the folder starting to tear panels as they are lifted as the speed of the folder is increased to match that of the printer/slotter. It will be appreciated that the lifter fingers are used for pulling back panels towards the front and of at least one portion of the blank with some sort of lifter finger or lifter device used on any machine that is producing lock bottom boxes. By slowing up the process, one can accomodate the rather stringent demands of the lock bottom boxes but it reduces the rate at which the overall system may operate such that, at the very least, the printer/slotter utilized is operated at no where near its maximum capability.
It will also be appreciated that many box manufacturers utilize relatively large presses in which, a common box blank may be printed and formed which typically has an overall length of 66". However, boxes having much shorter lengths such as 36" or 26" are also printed on the same machine. What happens with the smaller type box blanks on a larger type printing machine, is that while the printing machine is able to print at a relatively fast rate, if the folding machine is directly driven by the drive for the printing machine, an exorbitant amount of space is provided between the box blanks. This results in a process which can nowhere near reach the highest possible speed if the folder could be slowed down to close the inter-blank space. It was thought that this problem could not be solved with any substantial differential in speed between the printer/slotter and the folder due to registration problems and the aforementioned jamming which it was presumed would occur.
There was therefore a need to increase the production rate of the type of systems described above but it was not apparent that it could be done without significant jamming or running of a folding machine well beyond its rated speed capacity for the given job at hand.
Note that by the use of the term printer/slotter is meant in general a flexographic system in which either the printer, slotter, its associated feed and or associated die cutter may be used separately or in combination. Thus, the feed end of the printer/slotter may be used separately with the folder to process already printed and die-cut blanks.